CAMRT Radiography Practice Exam

What is the lower portion of the costal margin level with?

1. Mid thorax

2. Umbilicus

3. Xiphoid tip

4. Third lumbar vertebra

The correct answer is: Third lumbar vertebra

The lower portion of the costal margin is anatomically level with the third lumbar vertebra. The costal margin is formed by the lower edges of the rib cage, specifically the cartilages of the ribs that articulate with the sternum, and typically marks the boundary where the thoracic cavity transitions to the abdominal cavity. When performing imaging or assessing anatomical structures, it is important to correlate these landmarks with the vertebral levels to ensure accurate identification. In this case, the third lumbar vertebra serves as a key landmark for the point at which the costal margin aligns. This is particularly relevant in diagnostic imaging as certain organ systems and structures, like the kidneys, are located around this vertebral level, and understanding this relationship aids in effective assessment and treatment planning. Other options like mid thorax, umbilicus, and xiphoid tip indicate different anatomical references that do not correlate as accurately with the costal margin’s lower boundary, making them less suitable for this specific identification. The mid thorax is further up in the thoracic cavity, the umbilicus is located at a different abdominal level, and the xiphoid tip is higher, closer to the sternum. Thus, the third lumbar vertebra is the most accurate